Endocarditis: Symptoms, Types, Causes and Treatment

Endocarditis is a serious and potentially life-threatening condition characterized by inflammation and often infection of the inner lining of the heart, most commonly affecting the heart valves. Despite advancements in medical care, diagnosing and treating endocarditis remains challenging due to its varied symptoms, evolving causes, and complex management strategies. In this comprehensive guide, we explore the key symptoms, types, causes, and treatment approaches for endocarditis, drawing on the latest research to provide a clear and practical resource.

Symptoms of Endocarditis

Recognizing the symptoms of endocarditis can be difficult, as they often mimic other illnesses and can affect nearly every organ system in the body. Early identification is crucial for prompt treatment and better outcomes. The presentation can range from subtle constitutional symptoms to severe, organ-specific manifestations.

Symptom	Description	Frequency/Significance	Source(s)
Fever	Persistent or intermittent	Most common initial symptom	4 5 6 7 14
Heart murmur	New or changed cardiac murmur	Often present on examination	4 5 6 7
Back pain	Severe or moderate, sometimes disabling	May be initial or early sign	1 3 5
Musculoskeletal pain	Arthralgia, myalgia, arthritis	Often early, mimics rheumatic disease	1 3 5
Neurological symptoms	Stroke, headache, visual disturbances	Up to 29% of patients	2 4 8
Embolic events	Sudden organ dysfunction	Frequent complication	4 5 8
Petechiae	Small red or purple spots	Helpful in diagnosis	5
Fatigue, anorexia, weight loss	General malaise	Common constitutional symptoms	5 6

Table 1: Key Symptoms of Endocarditis

Constitutional and Cardiac Symptoms

• Fever: The most consistent symptom, often accompanied by chills and sweats. Fever may be persistent or intermittent, and in some cases, particularly in elderly or immunocompromised patients, it may be absent or low-grade 4 5 6 7 14.
• Heart Murmur: A new or changing murmur is a hallmark sign, resulting from infection-induced damage to heart valves. However, not all patients present with a murmur at the outset 4 5 6 7.

Musculoskeletal Manifestations

• Back Pain and Arthralgias: Musculoskeletal symptoms are common and sometimes the initial complaint. These include arthralgias (joint pain), arthritis (joint swelling), severe low back pain, myalgias (muscle pain), and occasionally, septic arthritis or discitis 1 3 5. These symptoms can mimic rheumatic diseases and may delay diagnosis.
• Prevalence: Up to 44% of patients experience musculoskeletal complaints, which are often monarticular or oligoarticular and can be disabling 1 3.

Neurological and Embolic Symptoms

• Neurological Complications: Neurological symptoms are present in up to 29% of cases and may include stroke, transient ischemic attacks, encephalopathy, meningitis, seizures, visual loss, and acute mononeuropathy 2 4 8. These complications arise from embolic events or direct infection.
• Embolic Events: Fragments of infected material (vegetations) can break off and travel to organs such as the brain, kidneys, or spleen, causing infarction or abscess formation 4 5 8.

Other Manifestations

• Petechiae: Tiny, non-blanching spots found on the skin, oral mucosa, or conjunctiva are helpful diagnostic clues 5.
• General Malaise: Fatigue, anorexia, and weight loss are common but non-specific 5 6.
• Renal, Ophthalmic, and Pulmonary Symptoms: Less frequently, endocarditis may present with hematuria (blood in urine), vision changes, or respiratory symptoms 5.

Types of Endocarditis

Endocarditis encompasses several distinct forms, each with unique features, causes, and clinical courses. Understanding the different types is essential for accurate diagnosis and tailored treatment.

Type	Key Features	Common Causes/Contexts	Source(s)
Infective	Caused by bacteria or fungi	Native/prosthetic valves, devices	6 7 8 10 11
Native Valve	Affects natural heart valves	Staphylococci, streptococci	4 6 11
Prosthetic Valve	Occurs on artificial valves	Staph. aureus, CoNS, fungi	4 6 11 12
Device-Related	Involves cardiac implants	Staph. aureus, CoNS	6 7 11
Nonbacterial Thrombotic (NBTE)	Sterile vegetations	Underlying malignancy, chronic disease	9
Culture-Negative	No organism isolated	Fastidious bacteria, prior antibiotics	8 12

Table 2: Main Types of Endocarditis

Infective Endocarditis

• Definition: Infection of the endocardial surface, most commonly affecting heart valves but also prosthetic material or devices 6 7 8.
• Subtypes:
  • Native Valve Endocarditis: Involves natural heart valves; most commonly caused by staphylococci and streptococci 4 6 11.
  • Prosthetic Valve Endocarditis: Involves artificial heart valves; often due to staphylococci, coagulase-negative staphylococci (CoNS), or fungi. Has a higher risk of serious complications 4 6 11 12.
  • Device-Related Endocarditis: Associated with pacemakers or other intracardiac devices; staphylococci are typical pathogens 6 7 11.

Nonbacterial Thrombotic Endocarditis (NBTE)

• Characteristics: Formation of sterile vegetations (non-infectious) on valve leaflets. Usually associated with underlying malignancies (e.g., carcinoma, leukemia) or chronic illness 9.
• Clinical Context: Often termed "marantic" or "Libman-Sacks" endocarditis in specific contexts, such as systemic lupus erythematosus 9.

Culture-Negative Endocarditis

• Definition: Clinical features of endocarditis without a causative organism identified in blood cultures 8 12.
• Causes: May result from fastidious organisms (e.g., HACEK group, Coxiella, Brucella, fungi) or prior antibiotic treatment 12.
• Diagnosis: Requires advanced microbiological techniques and close clinician-laboratory collaboration 12.

Causes of Endocarditis

The causative agents of endocarditis have shifted over time, influenced by medical practice changes, population aging, and increased device use. The most common culprits remain certain bacteria, but fungi and unusual organisms are gaining prominence in specific settings.

Cause/Agent	Typical Contexts	Notable Details	Source(s)
Staphylococcus aureus	Healthcare contact, IV drug use	Leading cause globally	4 6 10 11 14
Viridans group streptococci (VGS)	Dental procedures, native valves	Common in low-risk patients	11 14
Coagulase-negative staphylococci	Prosthetic valves, implants	Frequent in device cases	4 6 11 12
Enterococcus spp	Elderly, genitourinary sources	Rising incidence	11
Streptococcus gallolyticus (bovis)	GI tract, cancer association	Linked with embolic stroke	4 11
Fungi	Prosthetic valves, immunosuppressed	Up to 15% of prosthetic cases	12
HACEK group	Oral flora, culture-negative	Require special culturing	12
Gram-negative rods	Rare, device cases, IV drug use	Increasing but uncommon	13
Non-infectious (NBTE)	Malignancy, chronic diseases	Sterile vegetations	9

Table 3: Common Causes of Endocarditis

Bacterial Causes

• Staphylococcus aureus: Now the leading cause of endocarditis worldwide, particularly in healthcare-associated cases, patients with invasive devices, and people who inject drugs. S. aureus infections often present acutely and can be highly destructive 4 6 10 11 14.
• Viridans Group Streptococci: Traditionally common, especially after dental procedures or in patients with pre-existing valve abnormalities. Still important in certain populations 11 14.
• Coagulase-Negative Staphylococci (CoNS): Significant in prosthetic valve and device-related cases; often associated with chronic or subacute presentations 4 6 11 12.
• Enterococcus Species: Increasingly recognized, especially in elderly patients and those with genitourinary sources of infection 11.
• Streptococcus gallolyticus (bovis): Notable for its link with gastrointestinal malignancy and embolic stroke 4 11.

Fungal and Unusual Organisms

• Fungi: Account for up to 15% of prosthetic valve endocarditis. Risk factors include previous cardiac surgery, immunosuppression, and prolonged hospitalization 12.
• HACEK Group: Fastidious gram-negative organisms (e.g., Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella) are uncommon but important, especially in culture-negative cases. May require special microbiological techniques for detection 12.
• Other Fastidious Bacteria: Includes Coxiella burnetii (Q fever), Brucella, Chlamydia psittaci, and others. History of animal contact or travel may provide diagnostic clues 12.

Non-Infectious Causes

• Nonbacterial Thrombotic Endocarditis (NBTE): Characterized by sterile vegetations, seen in advanced malignancy, chronic wasting diseases, or autoimmune conditions 9.

Treatment of Endocarditis

The management of endocarditis requires a multidisciplinary approach, prompt initiation of targeted therapy, and close monitoring for complications. Recent advances are reshaping traditional treatment protocols, aiming to improve outcomes and reduce complications.

Treatment Approach	Key Features	Indications/Context	Source(s)
Intravenous antibiotics	Mainstay, prolonged course	All confirmed cases	14 15 16
Oral step-down antibiotics	After stabilization, selected patients	Non-inferior to IV in stable cases	16 18
Surgery	Valve replacement, abscess drainage	Heart failure, uncontrolled infection, large vegetations	4 14 15 17
Multidisciplinary care	Team-based, individualized plans	Improves outcomes	7 8 14 17

Table 4: Main Treatment Strategies for Endocarditis

Antibiotic Therapy

• Intravenous Antibiotics: The cornerstone of treatment. Therapy is tailored based on the causative organism and valve type (native vs. prosthetic). Courses typically last 4–6 weeks 14 15.
• Oral Step-Down Therapy: Recent studies support transitioning stable patients to oral antibiotics after an initial period of IV therapy, with outcomes comparable to prolonged IV regimens. This approach can reduce complications, hospital stays, and costs 16 18.
• Empiric Therapy: Initiated when blood cultures are pending or negative; should cover likely organisms and be adjusted once culture results are available 15.

Surgical Management

• Indications: Surgery is considered in cases of heart failure due to valve dysfunction, uncontrolled infection (e.g., abscess), large vegetations at risk of embolism, or prosthetic valve complications. Early surgical intervention may improve outcomes in selected patients 4 14 15 17.
• Procedures: May include valve repair/replacement or removal of infected devices 4 14 17.

Multidisciplinary and Supportive Care

• Team Approach: Management by a team including cardiologists, infectious disease specialists, cardiac surgeons, and others is essential for complex cases 7 8 14 17.
• Monitoring and Prevention: Regular follow-up to detect complications (e.g., embolic events, renal failure) and assess response to therapy is critical 14 17.
• Prophylaxis: The use of antibiotics before dental or invasive procedures remains controversial and is reserved for high-risk groups 6 14 15.

Emerging and Future Directions

• New Diagnostic Tools: Enhanced imaging and microbiological techniques are improving early detection, particularly in blood culture-negative cases 8 10 12.
• Vaccine Development: Research is ongoing to develop vaccines targeting common bacterial pathogens, though none are yet available 8.
• Long-term Follow-Up: Attention to late complications and prevention of recurrence is increasingly emphasized 17.

Conclusion

Endocarditis remains a complex and evolving disease, with high morbidity and mortality despite advances in medicine. Rapid diagnosis, individualized treatment, and multidisciplinary care are essential for improving patient outcomes.

Key Points:

• Endocarditis symptoms are diverse and may affect multiple organ systems, often mimicking other diseases.
• Types include infective (native/prosthetic/device-related), nonbacterial thrombotic, and culture-negative endocarditis.
• Staphylococcus aureus is now the leading cause, though a range of bacteria, fungi, and rare organisms are implicated.
• Treatment is based on prolonged antibiotics (IV and in some cases oral), with surgery for selected cases and multidisciplinary team management.
• Early recognition and tailored care are crucial to reducing complications and improving survival.

Understanding endocarditis in all its forms is vital for both clinicians and patients, empowering timely action and better outcomes.